Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

const regex = /^(?:[0-9A-Fa-f]+\s+){1,4}/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?:[0-9A-Fa-f]+\\s+){1,4}', 'gm') const str = `A92 6100 011E Bsr P6 A96 43EE 003A Lea.L \$3A(A6), A1 A9A 6100 013E Bsr P8 A9E 6608 BNE.B L90 AA0 4E91 Jsr (A1) AA2 70F5 MoveQ.L #\$-B, D0 AA4 6100 010C Bsr P6 AA8 43F8 0AD8 L90: Lea.L (SysResName), A1 AAC 76FF MoveQ.L #\$-1, D3 AAE 6100 012C Bsr P9 AB2 6600 0004 BNE L91 AB6 4E91 Jsr (A1) AB8 21F8 02A6 02B2 L91: Move.L (SysZone), (RAMBase) ABE 700C MoveQ.L #\$C, D0 AC0 A722 _NewHandleSysClear AC2 21C8 0AEC Move.L A0, (AppParmHandle) AC6 A02C _InitApplZone AC8 A04F _RDrvrInstall ACA 2F05 Move.L D5, -(A7)`; const subst = ``; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result);

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions